Especially in the USA, requirements imposed on tank containers are known. In accordance with FMVSS 301, such requirements require measures to be taken to prevent contact of a tube of 1200 mm in length with the surface of the fuel in the tank. The conditions have to be met even if the tank is virtually full. It is therefore necessary to introduce locks into the filling system of the motor vehicle in order to prevent siphoning off.
Theft protection means which are introduced into the filling system of a motor vehicle are known from the literature.
DE 20 2009 008494 discloses a theft protection means, which comprises a hollow cylinder having a casing surface and a basket formed from a base part extending perpendicularly to a centre axis of the filler neck. The basket comprises a basket material having a wide-meshed lattice structure and being provided with through-flow openings. The basket is braced in the interior of the filler neck by flanges and an O-ring and is held by stiction. This is an unsatisfactory solution, since the elasticity of plastics material rapidly diminishes especially in fuel mixtures having a high alcohol content, and secure anchoring is not provided over the service life of the vehicle.
DE 2360655 discloses star-disc-like locking elements which are pushed in the filler neck as far as possible in the direction of the tank. The discs are made of resilient material and the outside diameter of said discs is somewhat larger than the inside diameter of the filler neck. As a result, upon insertion, the arms of the locking elements spread against the inner wall of the filler neck and prevent a displacement in the longitudinal direction of the filler neck. This embodiment also has the weakness that all theft protection means introduced into the filler neck from the outside of the vehicle can be removed again with force.